Antenna and radio device

ABSTRACT

Two one-wavelength antenna elements ( 1 ) and ( 2 ) arranged in diamond-wise opposition to each other so that one-ends of the antenna elements ( 1 ) and ( 2 ) are provided with a feeding portion ( 3 ) and the other-ends ( 4 ) of the same are opened, and so that the angle (α) of each of bent portions ( 1   a ) and ( 2   a ) in the centers of the antenna elements ( 1 ) and ( 2 ) respectively is selected to be an optimal angle to obtain optimal radiation directivity with a simple configuration, thereby obtaining an antenna device which has a high gain. Accordingly, a small-size and low-profile antenna device can be obtained as a mobile communication antenna in UHF and submicro wave bands.

TECHNICAL FIELD

The present invention relates to an antenna device used in a mobilecommunication system such as a PHS or the like, and a radio apparatushaving the antenna device built therein.

BACKGROUND ART

Heretofore, a high gain was required of an antenna device used in aradio base station apparatus or fixed radio terminal apparatus in amobile communication system such as PHS or the like. Therefore, amultistage collinear array antenna was used, for example, as shown inJP-A-5-267932, JP-A-9-232851 and JP-A-8-139521. In the antenna of thistype, antennas non-directional in a horizontal plane with respect tovertically polarized wave were arranged multistageously vertically tonarrow directivity in a vertical plane to thereby secure a high gain.

An end-fire array antenna represented by a Yagi antenna or areflector-containing dipole antenna was also used, for example, as shownin JP-A-5-259733 and JP-A-8-304433. In the antenna of this type, passiveelements were arranged in parallel to the direction of main radiation tothereby secure a high gain.

A broadside array antenna represented by a patch array antenna wasfurther used, for example, as shown in JP-A-6-334434. In the antenna ofthis type, a plurality of antennas were arranged in a planeperpendicular to the direction of main radiation to perform distributivefeeding to thereby secure a high gain.

A low-profile antenna represented by a reflector-containing loop antennaor a slot antenna was further used, for example, as shown inJP-A-6-268432 and JP-U-6-44219.

On the other hand, an antenna formed from two one-wavelength antennasarranged into the form of a square or a circle, for example, as shownin“Antenna Handbook” (CQ Publication Co., Ltd.) p.366 is known as abroadside array antenna mainly used in a VHF band.

In the aforementioned conventional multistageous collinear arrayantenna, it was however necessary to arrange a large number of antennasvertically multistageously in order to secure a high gain. For example,a height of about 1 m was needed to obtain a gain of 10 dB in a 1900 MHzband. Hence, there was a problem in making sure of the antenna-settingspace and mechanical strength. Further, the antenna of this type wasunsuitable for being built in a radio apparatus because of its height.

Further, in the aforementioned conventional end-fire array antenna, itwas necessary to arrange a large number of antennas in the direction ofmain radiation in order to secure a high gain. Hence, there was aproblem in making sure of the antenna-setting space and mechanicalstrength. Further, the antenna of this type was unsuitable for beingbuilt in a radio apparatus because of its structure.

Further, in the conventional broadside array antenna, it was necessaryto arrange a large number of antennas in a plane perpendicular to thedirection of main radiation in order to secure a high gain. Hence, thetotal area of the antenna increased, so that there was a problem inmaking sure of the antenna-setting space and mechanical strength.Further, the antenna of this type was unsuitable for being built in aradio apparatus because of its large area.

In addition, although the conventional low-profile antenna was formed ina small-size low-profile configuration, there was a problem that theradiation directivity could not be optimized to provide desiredcharacteristic.

In the aforementioned antenna formed from two one-wavelength antennasarranged into the form of a square or a circle, only the radiationdirectivity in a predetermined vertical plane and in a predeterminedhorizontal plane could be obtained, and there was a problem that theradiation directivity could not be optimized to provide desiredcharacteristic.

The present invention is designed to solve the conventional variousproblems generally and it is an object of the present invention toprovide an antenna device in which the optimal radiation directivity canbe obtained in the broadside array antenna having two one-wavelengthantennas, in which a high gain and a high function can be obtained witha simple configuration and which can be used as a small-size low-profileantenna for a mobile communication system in UHF and sub-micro wavebands.

DISCLOSURE OF THE INVENTION

The present invention is devised so that the angle of bending in thecenter of each one-wavelength antenna element in a broadside arrayantenna having two one-wavelength antenna elements arranged therein isselected to be an optimal angle. Hence, there can be provided an antennadevice in which desired radiation directivity can be obtained with asimple configuration and which has a high gain.

Further, the present invention is devised so that a plurality ofantennas are connected in an opening portion at a forward end of each ofthe aforementioned antennas. Hence, there can be provided an antennadevice which has a high gain with a simple planar configuration.

Further, the present invention is devised so that a plurality ofantennas are connected in parallel with each other in a feeding portion.Hence, there can be provided an antenna device which has a high gainwith a simple planar configuration.

Further, the present invention is devised so that the aforementionedantennas are formed by a pattern printed on a dielectric substrate.Hence, there can be provided an antenna device in which desireddirectivity can be obtained with a small-size and simple configurationand which has a high gain.

Further, the present invention is devised so that the plurality ofantennas are connected to one another through transmission lines eachhaving a predetermined electrical length. Hence, there can be providedan antenna device in which the antenna as a whole can be extended in theY-plane direction easily, in which desired directivity can be obtainedand which has a high gain.

Further, the present invention is devised so that the two pairs ofaforementioned antennas are arranged with directions of mainpolarization perpendicular to each other and so that the antenna devicesare fed with phase differences of 90 degrees. Hence, there can beprovided an antenna device in which desired radiation directivity can beobtained with a simple planar configuration to achieve a circularpolarization antenna having a high gain.

Further, the present invention is devised so that the two pairs ofaforementioned antennas are formed by print patterns arranged onopposite surfaces of a dielectric substrate. Hence, there can beprovided an antenna device in which desired radiation directivity can beobtained with a small-size and simple planar configuration to achieve acircular polarization antenna having a high gain.

Further, the present invention is devised so that a reflection plate isprovided in proximity to the antenna. Hence, there can be provided anantenna device in which desired radiation directivity can be obtainedwith a simple planar configuration and which has a high gain.

Further, the present invention is devised so that a plurality of passiveelements are provided in proximity to the antenna. Hence, there can beprovided an antenna device in which desired radiation directivity can beobtained with a simple planar configuration and which has a high gain.

Further, the present invention is devised so that the aforementionedantennas are arranged as a radiator and a reflector while a plurality ofwave directors each having a shape similar to that of each of theantennas are arranged in the directions of the main radiation. Hence,there can be provided an antenna device in which desired radiationdirectivity can be obtained with a simple configuration and which has ahigh gain.

Further, the present invention is devised so that the two pairs ofaforementioned antennas are arranged with the directions of mainpolarization being made identical with each other and with thedirections of main radiation being made different from each other sothat the antennas are fed with phase differences of 90 degrees from eachother. Hence, there can be provided an antenna device in which desiredradiation directivity can be obtained with a simple configuration andwhich has a high gain.

Further, the present invention is devised so that the two pairs of afore mentioned antennas are arranged with the directions of the mainpolarization being made identical with each other and with thedirections of the main radiation being made different from each other.Hence, there can be provided an antenna device in which desiredradiation directivity can be obtained with a simple configuration andwhich has a high gain.

Further, the present invention is devised so that the plurality ofaforementioned antennas are arranged with the directions of the mainpolarization being made identical with one another and with thedirections of the main radiation being made different from one another,and controlling is performed such that the opposite antenna elements ofone or plural antenna devices among the plurality of antenna devices arepartially electronically connected to each other. Hence, there can beprovided an antenna device in which the radiation directivity can bechanged variously with a simple configuration and which has a high gain.

Further, the present invention is devised so that a quarter-wavelengthshorting stub is connected to a feeding point so that feeding isperformed at a position where the impedance of the shorting stub isoptimized. Hence, there can be provided an antenna device in which goodimpedance matching can be obtained by a small-size matching circuit witha simple configuration and which has a high gain.

Further, the present invention is devised so that an antenna devicecomprises a first one-wavelength slot element provided in a conductorplate so as to be bent at an angle α in the center of the first slotelement, and a second one-wavelength slot element provided in theconductor plate so as to be bent at an angle α in the center of thesecond slot element, wherein the first and second slot elements arearranged in diamond-wise opposition to each other and wherein respectiveone-ends of the first and second slot elements are connected to eachother to provide a feeding portion at the one-ends. Hence, there can beprovided an antenna device to achieve a slot antenna having a high gainwith a simple planar configuration.

Further, the present invention is devised so that, in the aforementionedslot antenna, the angle of bending in the center of each of theone-wavelength slot elements is selected to be an optimal angle toobtain optimal radiation directivity. Hence, there can be provided aslot antenna in which optimal radiation directivity can be obtained witha simple planar configuration and which has a high gain.

Further, the present invention is devised so that a plurality of slotantennas as described above are connected in the opening portion at theforward ends of the antennas. Hence, there can be provided an antennadevice to achieve a slot antenna having a high gain with a simple planarconfiguration.

Further, the present invention is devised so that a plurality of slotantennas as described above are connected in parallel to each other at afeeding portion. Hence, there can be provided an antenna device toachieve a slot antenna in which optimal radiation directivity can beobtained with a simple planar configuration and which has a high gain.

Further, the present invention is devised so that the plurality of slotantennas are formed by a print pattern formed on a dielectric substrate.Hence, there can be provided an antenna device to achieve a slot antennain which optimal radiation directivity can be obtained with a small-sizeand simple planar configuration and which has a high gain.

Further, the present invention is devised so that a reflection plate isprovided in proximity to the slot antenna. Hence, there can be providedan antenna device to achieve a slot antenna in which desired radiationdirectivity can be obtained with a simple planar configuration and whichhas a high gain.

Further, the present invention is devised so that a plurality of passiveelements are provided in proximity to the slot antenna. Hence, there canbe provided an antenna device to achieve a slot antenna in which desiredradiation directivity can be obtained with a simple configuration andwhich has a high gain.

Further, the present invention is devised so that the aforementionedantenna device is built in a radio apparatus. Hence, there can beprovided a radio apparatus with a built-in antenna in which desiredradiation directivity can be obtained and which has a high gain with asmall-size and simple configuration.

Further, the present invention is devised so that a plurality of antennadevices as described above are arranged to form a sector antenna devicefor a radio base station. Hence, there can be provided an antenna deviceto achieve a diversity antenna or a sector antenna in which desiredradiation directivity can be obtained with a small-size and simpleconfiguration and which has a high gain.

Further, the present invention is devised so that a reflection plate isprovided to be used in common to the plurality of antenna devices.Hence, there can be provided an antenna device to achieve a diversityantenna or a sector antenna in which desired radiation directivity canbe obtained with a small-size and simple configuration and which has ahigh gain.

Further, the present invention is devised so that a plurality ofantennas as described above are arranged to form a sector antenna devicefor a radio base station, and so that the sector antenna device isprovided in the radio base station. Hence, there can be provided a radiobase station with a built-in diversity or sector antenna in whichdesired radiation directivity can be obtained with a small-size andsimple configuration and which has a high gain.

Further, the present invention is devised so that each of two antennaelements arranged diamond-wise is bent at an angle a in its center, andso that the angle α is selected to be an angle at which optimalradiation directivity can be obtained. Hence, there can be provided amethod of controlling the directional gain of an antenna in whichdesired radiation directivity can be obtained with a simple planarconfiguration and which has a high gain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the configuration of an antenna deviceaccording to a first embodiment of the present invention;

FIG. 2 is a typical view for explaining the operation of the antennadevice shown in FIG. 1;

FIG. 3 is a graph showing the radiation pattern in a horizontal plane ofthe antenna device shown in FIG. 1;

FIG. 4 is a graph showing the radiation pattern in a vertical plane ofthe antenna device shown in FIG. 1; and

FIGS. 5 to 23 are views showing the configurations of antenna devicesaccording to second to twentieth embodiments of the present inventionrespectively.

BEST MODE FOR CARRYING OUT THE INVENTION

An antenna device according to one embodiment comprises a firstone-wavelength antenna element bent at an angle α in the center of thefirst antenna element, and a second one-wavelength antenna element bentat an angle α in the center of the second antenna element, wherein thefirst and second antenna elements are arranged in diamond-wiseopposition to each other, wherein a feeding portion is disposed atone-ends of the first and second antenna elements, wherein theother-ends of the first and second antenna elements are opened, andwherein the angle α is selected to be an optimal angle. Hence, optimalradiation directivity can be obtained with a simple planarconfiguration. Hence, there is an effect in which an antenna devicehaving a high gain can be obtained.

An antenna device according to another embodiment is configured so thata plurality of other first and second antenna elements are connected toforward ends of the first-mentioned first and second antenna elements.Hence, optimal radiation directivity improved in gain in the directionof main radiation can be obtained with a simple planar configuration.Hence, there is an effect in which an antenna device having a high gaincan be obtained.

An antenna device according to still another embodiment is configured sothat the angle α of bending in the center of each of the first andsecond antenna elements is selected to be an angle at which optimalradiation directivity can be obtained. Hence, optimal radiationdirectivity can be obtained with a simple planar configuration. Hence,there is an effect in which an antenna device having a high gain can beobtained.

An antenna device according to still another embodiment is configured sothat a plurality of antenna devices defined in an earlier embodiment areconnected in parallel with each other at the feeding portion. Hence,there is an effect in which an antenna device having a higher gain canbe obtained with a simple planar configuration.

An antenna device according to still another embodiment is configured sothat the angle α of bending in the center of each of the first andsecond antenna elements is selected to be an angle at which optimalradiation directivity can be obtained. Also in the case where aplurality of antenna devices are connected in parallel with each otherat a feeding point, optimal radiation directivity can be obtained with asmall-size and simple planar configuration. Hence, there is an effect inwhich an antenna device having a high gain can be obtained.

An antenna device according to still another embodiment is configured sothat the first and second antenna elements are formed by a print patternformed on a dielectric substrate. Also in the case where antennaelements are formed by a print pattern, desired radiation directivitycan be obtained with a small-size and simple planar configuration.Hence, there is an effect in which an antenna device having a high gaincan be obtained.

An antenna device according to still another embodiment is configured sothat the plurality of other first and second antenna elements areconnected to the first-mentioned first and second antenna elementsrespectively through transmission lines each having a fixed electricallength. Hence, the total length of the antenna can be elongated to adesired value in the Y-plane direction, so that desired radiationdirectivity can be obtained. Hence, there is an effect in which anantenna device having a high gain can be obtained.

An antenna device according to still another embodiment is configured sothat two pairs of antenna devices defined in earlier embodiments arearranged in such a manner that the directions of main polarizationcrossing perpendicularly to each other and the two pairs of antennadevices are fed with phase differences of 90 degrees from each other.Hence, desired radiation directivity can be obtained with a simpleplanar configuration. Hence, there is an effect in which an antennadevice to achieve a circular polarization antenna having a high gain canbe obtained.

An antenna device according to still another embodiment is configured sothat the antenna device defined in an earlier embodiment is formed byprint patterns disposed on opposite surfaces of a dielectric substrate.Also in the case where two pairs of antenna devices are formed by printpatterns with the directions of main polarization crossingperpendicularly to each other, desired radiation directivity can beobtained with a small-size and simple planar configuration. Hence, thereis an effect in which an antenna device to achieve a circularpolarization antenna having a high gain can be obtained.

An antenna device according to still another embodiment is configured sothat the antenna devices defined in an earlier embodiment are arrangedin such a manner that the directions of main polarization crossperpendicularly to each other, and the plurality of antenna devices arefed with phase differences of 90 degrees from each other. Hence, desiredradiation directivity can be obtained with a simple planarconfiguration. Hence, there is an effect in which an antenna device toachieve a circular polarization antenna having a high gain can beobtained.

An antenna device according to still another embodiment is configured sothat a reflection plate is provided in proximity to the antennaelements. Hence, desired radiation directivity can be obtained with asimple planar configuration. Hence, there is an effect in which anantenna device having a higher gain can be obtained.

An antenna device according to still another embodiment is configured sothat a plurality of passive elements are provided in proximity to theantenna elements. Hence, desired radiation directivity can be obtainedwith a simple planar configuration. Hence, there is an effect in whichan antenna device having a high gain can be obtained.

An antenna device according to still another embodiment is configured sothat antenna devices defined in earlier embodiments are arranged as aradiator and a reflector, and a plurality of wave directors which aresimilar in shape to the antenna devices are arranged in the directionsof main radiation. Hence, desired radiation directivity can be obtainedwith a simple configuration. Hence, there is an effect in which anantenna device having a higher gain can be obtained.

An antenna device according to still another embodiment is configured sothat antenna devices defined in earlier embodiments are arranged in sucha manner that the directions of main polarization are made identicalwith one another while the directions of main radiation are madedifferent by 90 degrees from one another, and the plurality of antennasare fed with phase differences of 90 degrees from one another. Hence,desired radiation directivity can be obtained with a simpleconfiguration. Hence, there is an effect in which an antenna devicehaving a high gain can be obtained.

An antenna device according to still another embodiment is configured sothat two pairs of antenna devices defined in earlier embodiments arearranged in such a manner that the directions of main polarization aremade identical with each other while the directions of main radiationare made different from each other. Hence, desired radiation directivitycan be obtained with a simple configuration. Hence, there is an effectin which an antenna device having a high gain can be obtained.

An antenna device according to still another embodiment is configured sothat a plurality of antenna devices defined in earlier embodiments arearranged in such a manner that the directions of main polarization aremade identical with each other while the directions of main radiationare made different from each other, and opposite antenna elements of atleast one antenna device among the plurality of antenna devices arepartially electronically connected/disconnected to/from each other.Hence, radiation directivity can be changed variously with a simpleconfiguration so as to obtain a desired radiation direction. Hence,there is an effect in which a changeable directional antenna devicehaving a high gain can be obtained.

An antenna device according to still another embodiment is configured sothat a quarter-wavelength shorting stub is connected to a feeding pointso that feeding is performed at a position where impedance of theshorting stub is optimized. Hence, good impedance matching can beobtained by a small-size matching circuit with a simple configuration.Hence, there is an effect in which an antenna device having a high gaincan be obtained.

An antenna device according to still another embodiment comprises afirst one-wavelength slot element provided in a conductor plate so as tobe bent at an angle α in the center of the first slot element, and asecond one-wavelength slot element provided in the conductor plate so asto be bent at an angle α in the center of the second slot element,wherein the first and second slot elements are arranged in diamond-wiseopposition to each other, and wherein a feeding portion is disposed inone-ends of the first and second slot elements. Hence, desired radiationdirectivity can be obtained with a simple planar configuration. Hence,there is an effect in which a slot antenna having a high gain can beachieved.

An antenna device according to still another embodiment is configured sothat the angle α is selected to be an angle at which optimal radiationdirectivity can be obtained. Hence, optimal radiation directivity can beobtained with a simple planar configuration. Hence, there is an effectin which a slot antenna having a high gain can be achieved.

An antenna device according to still another embodiment is configured sothat a plurality of other first and second slot elements are connectedto forward ends of the first-mentioned first and second slot elements.Hence, there is an effect in which a slot antenna having a high gainfurther improved in gain in the direction of main radiation can beachieved with a simple planar configuration.

An antenna device according to still another embodiment is configured sothat the angle α is selected to be an angle at which optimal radiationdirectivity can be obtained. Hence, optimal radiation directivity can beobtained with a simple planar configuration. Hence, there is an effectin which a slot antenna having a high gain can be achieved.

An antenna device according to still another embodiment is configured sothat a plurality of antenna devices defined in an earlier embodiment areconnected in parallel with one another at a feeding portion. Hence,there is an effect in which a slot antenna having a higher gain can beachieved with a simple planar configuration.

An antenna device according to still another embodiment is configured sothat the angle α is selected to be an angle at which optimal radiationdirectivity can be obtained. Hence, optimal radiation directivity can beobtained with a simple planar configuration. Hence, there is an effectin which a slot antenna having a high gain can be achieved.

An antenna device according to still another embodiment is configured sothat the conductor plate and the slot elements are constituted by aprint pattern formed on a dielectric substrate. Hence, optimal radiationdirectivity can be obtained with a small-size and simple planarconfiguration. Hence, there is an effect in which a slot antenna havinga high gain can be achieved.

An antenna device according to still another embodiment is configured sothat a reflection plate is provided in proximity to the conductor plateand the slot elements. Hence, desired radiation directivity can beobtained with a simple configuration. Hence, there is an effect in whicha slot antenna having a higher gain can be achieved.

An antenna device according to still another embodiment is configured sothat a plurality of passive elements are provided in proximity to theantenna elements. Hence, desired radiation directivity can be obtainedwith a simple configuration. Hence, there is an effect in which a slotantenna having a high gain can be achieved.

A radio apparatus according to still another embodiment is configured sothat an antenna device defined in earlier embodiments is built in theradio apparatus. Hence, desired optimal radiation directivity can beobtained. Hence, there is an effect in which an antenna having a highgain can be built in a radio apparatus with a small-size and simpleconfiguration.

An antenna device according to still another embodiment is configured sothat a plurality of antenna devices defined in earlier embodiments arearranged. Hence, desired radiation directivity can be obtained with asmall-size and simple configuration. Hence, there is an effect in whicha diversity or sector antenna having a high gain can be achieved.

An antenna device according to still another embodiment is configured sothat a reflection plate is provided so as to be used in common to theplurality of antenna devices. Hence, desired radiation directivity canbe obtained with a small-size and simple configuration. Hence, there isan effect in which a diversity or sector antenna having a high gain canbe achieved.

A radio base station according to still another embodiment is configuredso that the radio base station is provided with an antenna devicedefined in an earlier embodiment. Hence, desired radiation directivitycan be obtained with a small-size and simple configuration. Hence, thereis an effect in which a diversity or sector antenna having a high gaincan be used.

A directional gain control method according to still another embodimentis configured so that first and second antenna elements constituting anantenna device are arranged in diamond-wise opposition to each other,the first and second antenna elements having one-ends fed and theother-ends opened, each of the first and second antenna elements is bentat an angle α in a center thereof, and the angle α is selected to be anangle at which optimal radiation directivity can be obtained. Hence,desired optimal radiation directivity can be obtained with a simpleplanar configuration. Hence, there is an effect in which a method ofcontrolling the directional gain of an antenna having a high gain can beobtained.

Embodiments of the present invention will be described below in detailwith reference to the accompanying drawings FIGS. 1 through 23.

First Embodiment

First, an antenna device according to a first embodiment of the presentinvention will be described in detail with reference to FIGS. 1 through4. FIG. 1 is a view showing the configuration of the antenna deviceaccording to the first embodiment of the present invention. FIG. 2 is atypical view for explaining the operation of the antenna device shown inFIG. 1. FIG. 3 is a graph showing the radiation pattern in a horizontalplane of the antenna device shown in FIG. 1. FIG. 4 is a graph showingthe radiation pattern in a vertical plane of the antenna device shown inFIG. 1.

Referring to FIG. 1, the configuration of the antenna device accordingto the first embodiment of the present invention will be describedbelow. In FIG. 1, the reference numeral 1 designates a first antennaelement; 2, a second antenna element; 3, a feeding portion; 4, anopening portion; and 1 a and 2 a, bent portions.

Next, the configuration of the antenna device according to thisembodiment will be described in more detail. Each of the first andsecond antenna elements 1 and 2 is constituted by a conductor wire witha length of one wavelength. The first and second antenna elements 1 and2 are bent at an angle α in the bent portions 1 a and 2 a respectively.The first and second antenna elements 1 and 2 are arranged indiamond-wise opposition to each other as shown in FIG. 1. Each side ofthe diamond shape has a half wavelength (λ/2). The feeding portion 3 isprovided at one-ends of the first and second antenna elements 1 and 2respectively. The other-ends of the first and second antenna elements 1and 2 are electrically opened as represented by the opening portion 4.When, for example, the operating frequency of the antenna device is setto 1900 MHz, the length of each of the first and second antenna elements1 and 2 is about 158 mm and each side of the diamond shape is 79 mm. Theangle α is selected to be approximately in a range of from 30 to 150degrees.

Referring to FIGS. 2 through 4, the operation of the antenna deviceaccording to this embodiment will be described below. In the antennadevice configured as shown in FIG. 1, when the feeding portion 3 isexcited by a high-frequency signal, currents distributed in the firstand second antenna elements 1 and 2 are as represented by the arrows 5 ato 5 d because each side of the diamond shape has a half wavelength(λ/2). As a result, the antenna device operates so that respectivehorizontal components (Y-axis components) of the currents 5 a to 5 dcancel one another whereas respective vertical components (Z-axiscomponents) of the currents 5 a to 5 d intensify one another. Thus,vertically (Z-axis) polarized electric wave is radiated. The radiationof the vertically (Z-axis) polarized electric wave is maximized in the Xdirection and in the −X direction in FIG. 1. In this case, a directionalgain of about 6 dB is obtained.

This operation is equivalent to that of an array antenna constituted byfour half-wavelength dipole antennas arranged as shown in FIG. 2. InFIG. 2, the reference numerals 6a to 6 d designate vertical polarizationhalf-wavelength dipole antennas. The dipole antennas 6 a to 6 d arearranged with vertical and horizontal arrangement intervals determinedon the basis of the angle α′ and distance S between the dipole antennas6 a to 6 d. When the dipole antennas 6 a to 6 d are excited by in-phaseand equiamplitude signals respectively, intensive radiation synthesizedin the X-axis direction is generated. The pattern of the radiation isdetermined on the basis of arrangement coefficients owing to thevertical and horizontal arrangement intervals.

In FIG. 2, when the distance S is fixed to about 0.32λ (0.32 times aslarge as the wavelength), the change of the radiation pattern in thecase where the angle α of each of the bent portions 1 a and 2 a of thefirst and second antenna elements 1 and 2 in the antenna deviceaccording to the first embodiment as shown in FIG. 1 is changed isapproximately equal to the change of the radiation pattern in the casewhere the angle α′ between the dipole antennas 6 a to 6 d in the arrayantenna shown in FIG. 2 is changed. This state will be described belowwith reference to FIGS. 3 and 4.

FIG. 3 is a graph showing the radiation pattern of vertically polarizedwave in a horizontal plane (XY plane) in each of the antenna devicesshown in FIGS. 1 and 2. The horizontal axis indicates an angle (degrees)of radiation and the angle of 0 degree indicates the X direction. Thevertical axis indicates a radiation level relative value normalized by alevel in a maximum radiation direction. In FIG. 3, the reference numeral7 designates a radiation pattern in the case where the angle α of eachof the bent portions 1 a and 2 a of the antenna device in FIG. 1 isequal to 60 degrees. The reference numeral 8 designates a radiationpattern in the case where the angle α′ between the dipole antennas inFIG. 2 is equal to 60 degrees. The reference numeral 9 designates aradiation pattern in the case where the angle α of each of the bentportions 1 a and 2 a of the antenna device in FIG. 1 is equal to 120degrees. The reference numeral 10 designates a radiation pattern in thecase where the angle α′ between the dipole antennas in FIG. 2 is equalto 120 degrees.

Next, FIG. 4 is a graph showing the radiation pattern of verticallypolarized wave in a vertical plane (XZ plane) in each of the antennadevices shown in FIGS. 1 and 2. In FIG. 4, the reference numerals 7 to10 designate radiation patterns similar to those in FIG. 3. Here, bychanging the angle α of each of the bent portions 1 a and 2 a in theantenna device according to the first embodiment as shown in FIG. 1, theradiation patterns in the horizontal plane and in the vertical plane canbe changed greatly. When, for example, the angle α is changed toincrease from 60 degrees to 120 degrees, the half-value width (the widthof the radiation angle to obtain −3 dB) of the radiation pattern in thehorizontal plane decreases from 118 degrees to 64 degrees, while thehalf-value width of the radiation pattern in the vertical planeincreases from 50 degrees to 68 degrees. The array antenna shown in FIG.2 has this tendency similarly. When, for example, the angle α of each ofthe bent portions 1 a and 2 a is changed to increase from 30 degrees to150 degrees, the half-value width of the radiation pattern in thehorizontal plane changes from approximately non-directivity to 47degrees and the half-value width of the radiation pattern in thevertical plane increases from 50 degrees to 80 degrees.

Although this embodiment has shown the case where the direction of mainpolarization is vertical (Z), the same operation as described above canbe carried out by a horizontal polarization antenna in the case wherethe antenna device in FIG. 1 is arranged to be rotated by 90 degrees sothat the direction of main polarization is changed to horizontal (Y).

As described above, in the antenna device according to the firstembodiment, radiation patterns in the horizontal plane and in thevertical plane can be controlled by changing the angle α. Hence, anantenna having desired directivity and having a high gain can beachieved with a simple planar configuration.

Second Embodiment

Referring to FIG. 5, an antenna device according to a second embodimentof the present invention will be described below. FIG. 5 is a viewshowing the configuration of the antenna device according to the secondembodiment of the present invention. In FIG. 5, the reference numeral 3designates a feeding portion; 4, an opening portion; 11, a first antennaelement; 12, a second antenna element; and 11 a, 11 b, 11 c, 12 a, 12 band 12 c, bent portions.

Further, the configuration of the antenna device according to thisembodiment will be described in more detail. As shown in FIG. 5, thefirst and second antenna elements 11 and 12 are arranged so oppositelythat two diamond-shaped antenna devices each constituted by first andsecond antenna elements 1 and 2 as shown in FIG. 1 are connected to eachother. The length of each side of the diamond shape is equal to a halfwavelength (λ/2). That is, each of the first and second antenna elements11 and 12 is constituted by a conductive wire having a length equal totwo wavelengths. The first and second antenna elements 11 and 12 arebent at an angle α in the bent portions 11 a to 11 c and 12 a to 12 crespectively. The feeding portion 3 is provided at one-ends of the firstand second antenna elements 11 and 12 respectively. The opposite ends ofthe first and second antenna elements 11 and 12 are electrically openedas shown by the opening portion 4.

Referring to FIG. 5, the operation of the antenna device according tothis embodiment will be described below. In the antenna deviceconfigured as described above, when the feeding portion 3 is excited bya high-frequency signal, currents distributed into respective sides ofthe first and second antenna elements 11 and 12 are as indicated by thearrows 13 a to 13 h because the length of each side of the diamond shapeis equal to a half wavelength (λ/2). As a result, an operation iscarried out so that horizontal components (Y-axis components) of therespective currents cancel one another while vertical components (Z-axiscomponents) of the respective currents intensify one another. Hence,vertically (Z-axis) polarized electric wave is radiated. The radiationof electric wave is maximized in the X direction and in the −X directionin FIG. 5, so that a directional gain of about 9 dB is obtained.

This operation is approximately equivalent to the operation of an arrayantenna in which two antenna devices according to the first embodimentas shown in FIG. 1 are arranged in the Y direction. Hence, in theantenna device according to the second embodiment in FIG. 5, radiationpatterns in the horizontal plane and in the vertical plane can bechanged greatly by changing the angle α. When, for example, the angle αis changed to increase from 60 degrees to 120 degrees, the half-valuewidth of the radiation pattern in the horizontal plane decreases from 50degrees to 30 degrees while the half-value width of the radiationpattern in the vertical plane increases from 50 degrees to 68 degrees.Here, the half-value width of the radiation pattern in the horizontalplane is reduced to about a half compared with the antenna deviceaccording to the first embodiment as shown in FIG. 1.

Incidentally, in the case where a plurality of antenna elements ofdiamond-shapes are connected to form one antenna device like in thisembodiment, if the bent portions 11 b and 12 b which form junctionportions of the diamond shapes are cut off, the diamond shapes areseparated from each other. Then, if the first antenna elements 11 cutoff thus are connected to each other again through a transmission linehaving a fixed electrical length whereas the second antenna elements 12cut off thus are also connected to each other through a transmissionline having a fixed electrical length, the whole length of the antennadevice can be controlled if it is desired.

As described above, in the antenna device according to this embodiment,radiation patterns in the horizontal plane and in the vertical plane canbe controlled by changing the angle α. Hence, an antenna having desireddirectivity and having a high gain can be achieved with a simple planarconfiguration.

Third Embodiment

Referring to FIG. 6, an antenna device according to a third embodimentof the present invention will be described below. FIG. 6 is a viewshowing the configuration of the antenna device according to the thirdembodiment of the present invention. In FIG. 6, the reference numeral 3designates a feeding portion; 4 a and 4 b, opening portions; 14 and 15,first antenna elements; 16 and 17, second antenna elements; and 14 a, 15a, 16 a and 17 a, bent portions.

Further, the configuration of the antenna device according to thisembodiment will be described in more detail. Each of the first andsecond antenna elements 14 to 17 is constituted by a conductive wirehaving a length equal to one wavelength. The first and second antennaelements 14 to 17 are bent at an angle α in the bent portions 14 a to 17a respectively. The first antenna elements 14 and 15 and the secondantenna elements 16 and 17 are connected as shown in FIG. 6. The feedingportion 3 is provided in junction portions between the first antennaelements 14 and 15 and between the second antenna elements 16 and 17.Other ends are electrically opened as represented by the openingportions 4 a and 4 b.

Referring to FIG. 6, the operation of the antenna device according tothis embodiment will be described below. In the antenna deviceconfigured as described above, when the feeding portion 3 is excited bya high-frequency signal, currents distributed into respective sides ofthe first and second antenna elements 14 to 17 flow as indicated by thearrows 18 a to 18 h because the length of each side of the diamond shapeis equal to a half wavelength (λ/2). As a result, an operation iscarried out so that horizontal components (Y-axis components) of therespective currents cancel one another while vertical components (Z-axiscomponents) of the respective currents intensify one another. Hence,vertically (Z-axis) polarized electric wave is radiated. The radiationof vertically (Z-axis) polarized electric wave is maximized in the Xdirection and in the −X direction in FIG. 6, so that a directional gainof about 9 dB is obtained.

This operation is approximately equivalent to the operation of an arrayantenna in which two antenna devices according to the first embodimentas shown in FIG. 1 are arranged so as to be fed in parallel in the Ydirection. Hence, in the antenna device according to the thirdembodiment in FIG. 6, the change of radiation patterns in the case wherethe angle α is changed is approximately equivalent to that in theantenna device according to the second element in FIG. 5. Further,feeding-point impedance is reduced to a value not higher than a half ofthat of the antenna device according to the first embodiment as shown inFIG. 1 to be thereby favorable for matching the impedance with thetransmission line.

Although this embodiment has shown the case where antenna devices asshown in FIG. 1 are fed in parallel, the same effect as described abovecan be obtained also in the case where antenna devices as shown in FIG.5 are fed in parallel.

As described above, in the antenna device according to the thirdembodiment, the feeding-point impedance can be reduced and the radiationpatterns in the horizontal plane and in the vertical plane can becontrolled by changing the angle α. Hence, an antenna having desireddirectivity and having a high gain can be achieved with a simple planarconfiguration.

Fourth Embodiment

Referring to FIG. 7, an antenna device according to a fourth embodimentof the present invention will be described below. FIG. 7 is a viewshowing the configuration of the antenna device according to the fourthembodiment of the present invention. In FIG. 7, the reference numeral 4designates an opening portion; 19, a dielectric substrate; 20, a firstantenna pattern as a first antenna element; 21, a second antenna patternas a second antenna element; 22 and 23, feeding terminals; and 20 a and21 a, bent portions.

Further, the configuration of the antenna device according to thisembodiment will be described in more detail. Each of the first andsecond antenna patterns 20 and 21 is constituted by a print patternformed on the dielectric substrate 19. The first and second antennapatterns 20 and 21 are bent at an angle α in the bent portions 20 a and21 a respectively. The length of each of the first and second antennapatterns 20 and 21 is selected to be equal to one wavelength on thedielectric substrate. When, for example, the effective relativedielectric constant of the dielectric substrate is 2, the length of eachof the first and second antenna patterns 20 and 21 is about 80 mm forthe operating frequency of 1900 MHz because the wavelength on thedielectric substrate is reduced to about a half of the wavelength in afree space.

Referring to FIG. 7, the operation of the antenna device according tothis embodiment will be described below. In the antenna deviceconfigured as described above, when the feeding terminals 22 and 23 areexcited by a high-frequency signal, the antenna device operates in thesame manner as in the antenna device according to the first embodimentin FIG. 1. Hence, more detailed description will be omitted.

As described above, in the antenna device according to the fourthembodiment, an antenna having desired directivity and having a high gaincan be achieved with a small-size and simple planar configuration by aprint pattern on a dielectric substrate.

Fifth Embodiment

Referring to FIG. 8, an antenna device according to a fifth embodimentof the present invention will be described below. FIG. 8 is a viewshowing the configuration of the antenna device according to the fifthembodiment of the present invention. In FIG. 8, the reference numeral 24designates a dielectric substrate; 25, 26, 27 and 28, antenna patternsas antenna elements; 29, 30, 31 and 31, feeding terminals; and 33 and34, high-frequency signal sources.

Further, the configuration of the antenna device according to thisembodiment will be described in more detail. The antenna patterns 25 and26 are constituted by a print pattern formed on one surface of thedouble-side copper-clad dielectric substrate 24, while the antennapatterns 27 and 28 are constituted by a print pattern formed on theother surface of the double-side copper-clad dielectric substrate 24.The length of each of the antenna patterns 25, 26, 27 and 28 is selectedto be equal to one wavelength on the dielectric substrate. A combinationof the antenna patterns 25 and 26 and the feeding portions 29 and 30 anda combination of the antenna patterns 27 and 28 and the feeding portions31 and 32 serve as independent antennas. Each of the antennas operatesin the same manner as in the antenna device according to the fourthembodiment in FIG. 7.

Referring to FIG. 8, the operation of the antenna device according tothis embodiment will be described below. In the antenna deviceconfigured as described above, when excitation is given from thehigh-frequency signal sources 33 and 34, the antenna patterns 25 and 26radiate vertically (Z-direction) polarized wave whereas the antennapatterns 27 and 28 radiate horizontally (Y-direction) polarized wave.Hence, when the phases of the high-frequency signal sources 33 and 34are selected to be made different by 90 degrees from each other,circularly polarized electric wave is radiated in the X direction and inthe −X direction, so that a directional gain of about 6 dB is obtained.Further, left-handed circularly polarized wave or right-handedcircularly polarized wave is radiated either in the X direction or inthe −X direction. The rotational direction is determined on the basis ofthe lag-lead relation between the phases of the high-frequency signalsources 33 and 34.

Incidentally, although this embodiment has shown the case where theantenna device is formed on the dielectric substrate, the same effect asdescribed above can be obtained also in the case where two pairs ofantenna devices as shown in FIG. 1 are arranged with directions ofpolarization crossing perpendicularly to each other.

As described above, in the antenna device according to the fifthembodiment, a circular polarization antenna having desired directivityand having a high gain can be achieved with a small-size and simpleplanar configuration by print patterns on a dielectric substrate.

Sixth Embodiment

Referring to FIG. 9, an antenna device according to a sixth embodimentof the present invention will be described below. FIG. 9 is a viewshowing the configuration of the antenna device according to the sixthembodiment of the present invention. In FIG. 9, the reference numerals33 and 34 designate high-frequency signal sources; 35, 36, 37, 38, 39,40, 41 and 42, antenna elements; 43, a horizontal polarization antennasystem; and 44, a vertical polarization antenna system.

Referring to FIG. 9, the operation of the antenna device according tothis embodiment will be described below. The antenna elements 35, 36 and39, 40 are excited by the high-frequency signal source 33, so that theyserve as a horizontal polarization antenna system 43 which operates inthe same manner as the antenna device according to the third embodimentin FIG. 6. The antenna elements 38, 39 and 41, 42 are excited by thehigh-frequency signal source 34, so that they serve as a verticalpolarization antenna system 44 which operates in the same manner as theantenna device according to the third embodiment in FIG. 6.

The horizontal polarization antenna system 43 and the verticalpolarization antenna system 44 are arranged so as to crossperpendicularly to each other in the YZ plane. Hence, when the phases ofthe high-frequency signal sources 33 and 34 are selected to be madedifferent by 90 degrees from each other, circular lypolarized electricwave is radiated in the X direction and in the −X direction, so that adirectional gain of about 8 dB is obtained. Further, left-handedcircularly polarized wave or right-handed circularly polarized wave isradiated either in the X direction or in the −X direction. Therotational direction is determined on the basis of the lag-lead relationbetween the phases of the high-frequency signal sources 33 and 34.

As described above, in the antenna device according to the sixthembodiment, a circular polarization antenna having desired directivityand having a high gain can be achieved with a simple planarconfiguration.

Seventh Embodiment

Referring to FIG. 10, an antenna device according to a seventhembodiment of the present invention will be described below. FIG. 10 isa view showing the configuration of the antenna device according to theseventh embodiment of the present invention. In FIG. 10, the referencenumeral 3 designates a feeding portion; 45, a reflection plate; and 46and 47, antenna elements.

Referring to FIG. 10, the operation of the antenna device according tothis embodiment will be described below. The antenna elements 46 and 47operate in the same manner as in the antenna device according to thefirst embodiment in FIG. 1, so that maximum radiation is generated inthe X direction and in the −X direction. In this embodiment, however,the antenna elements 46 and 47 are arranged so as to be distanced fromthe reflection plate 45 by a distance indicated by the reference numeral48. The wave radiated in the −X direction is reflected by the reflectionplate 45, so that the reflected wave is radiated in the X direction.Hence, radiation patterns are concentrated into the X direction. Whenthe distance 48 is selected to be about 0.3λ(0.3 times as large as thewavelength), a directional gain of about 9.5 dB can be obtained in the Xdirection.

Incidentally, also in this embodiment, radiation patterns in thehorizontal plane and in the vertical plane can be controlled by changingthe angle α in the bent portions.

As described above, in the antenna device according to the seventhembodiment, an antenna device having desired directivity and having ahigh gain can be achieved with a simple planar configuration.

Eighth Embodiment

Referring to FIG. 11, an antenna device according to an eighthembodiment of the present invention will be described below. FIG. 11 isa view showing the configuration of the antenna device according to theeighth embodiment of the present invention. In FIG. 11, the referencenumeral 3 designates a feeding portion; 49, a reflection plate; 50 and51, antenna elements; and 52 and 53, passive elements.

Referring to FIG. 11, the detailed configuration and operation of theantenna device according to this embodiment will be described below. Theantenna elements 50 and 51 operate in the same manner as in the antennadevice according to the first embodiment in FIG. 1. Further, the antennaelements 50 and 51 are arranged so as to be separated by a distance 54from the reflection plate 49. Each of the passive elements 52 and 53 isconstituted by a conductive wire which is slightly shorter than a halfwavelength. The passive elements 52 and 53 are arranged in positionswhich are separated by a distance 55 in the X direction from the antennaelements 52 and 53 and which are separated by a distance 56 in the Y and−Y directions from the center respectively. When each of the distances54 and 55 is selected to be about 0.3λ (0.3 times as large as thewavelength) and the distance 56 is selected to be about 0.4λ (0.4 timesas large as the wavelength), wide-angle directivity of 180 degrees as ahalf-value width can be obtained in the X direction, so that adirectional gain of about 6.5 dB can be obtained.

As described above, in the antenna device according to the eighthembodiment, an antenna device having wide-angle directivity of 180degrees as a half-value width and having a high gain can be achievedwith a simple configuration.

Ninth Embodiment

Referring to FIG. 12, an antenna device according to a ninth embodimentof the present invention will be described below. FIG. 12 is a viewshowing the configuration of the antenna device according to the ninthembodiment of the present invention. In FIG. 12, the reference numeral 3designates a feeding portion; and 57, 58, 59, 60, 61 and 62, antennaelements.

Referring to FIG. 12, the operation of the antenna device according tothis embodiment will be described below. The antenna elements 57 and 58and the feeding portion 3 operate in the same manner as in the antennadevice according to the first embodiment in FIG. 1, so that they serveas a radiator. Each of the antenna elements 59 and 60 is selected tohave a length longer by about 4% than that of each of the antennaelements 57 and 58. The antenna elements 59 and 60 are arranged so as tobe separated by about 0.2λ (0.2 times as large as the wavelength) in the−X direction from the antenna elements 57 and 58, so that they serve asa reflector. Further, each of the antenna elements 61 and 62 is selectedto have a length shorter by about 8% than that of each of the antennaelements 57 and 58. The antenna elements 61 and 62 are arranged so as tobe separated by about 0.2λ (0.2 times as large as the wavelength) in theX direction from the antenna elements 57 and 58, so that they serve as awave director.

The antenna device configured as described above operates as a whole inthe same manner as a Yagi antenna. Hence, radiation directivity isconcentrated into the X direction, so that a directional gain of about11 dB is obtained.

Although this embodiment has shown the case where a three-element Yagiantenna is formed, a higher gain can be obtained if a larger number ofelements are arranged. When, for example, 5 elements are provided, adirectional gain of about 12.5 dB can be obtained. Also in thisembodiment, directivity in the vertical plane and in the horizontalplane can be changed by changing the angle α in the bent portions.

As described above, in the antenna device according to the ninthembodiment, a Yagi antenna having desired directivity and having a highgain can be achieved with a simple configuration.

Tenth Embodiment

Referring to FIG. 13, an antenna device according to a tenth embodimentof the present invention will be described below. FIG. 13 is a viewshowing the configuration of the antenna device according to the tenthembodiment of the present invention. In FIG. 13, the reference numerals63, 64, 65 and 66designate antenna elements; and 67 and 68,high-frequency signal sources.

Referring to FIG. 13, the detailed configuration and operation of theantenna device according to this embodiment will be described below. Theantenna elements 63 and 64 and the feeding portion 67 operate in thesame manner as in the antenna device according to the first embodimentin FIG. 1. The antenna elements 65 and 66 and the feeding portion 68also operate in the same manner as in the antenna device according tothe first embodiment in FIG. 1. The antenna elements 63, 64 and 65, 66are arranged so that the direction of main polarization in the antennaelements 63 and 64 is identical with that in the antenna elements 65 and66 in terms of horizontally polarized wave, whereas the directions ofmain radiation cross perpendicularly to each other.

When the antenna element 63 and 64 and the antenna element pair 65 and66 are supplied with high-frequency signals 67 and 68 respectively sothat the phases of the signals are made different by 90 degrees fromeach other, the antenna device exhibits non-directional radiationcharacteristic in the horizontal plane in terms of horizontallypolarized wave, so that a gain of about 3.5 dB can be obtained.

Also in this embodiment, directivity in the vertical plane and in thehorizontal plane can be changed by changing the angle α in the bentportions.

As described above, in the antenna device according to the tenthembodiment, a horizontal non-directional antenna having a high gain canbe achieved with a simple configuration.

Eleventh Embodiment

Referring to FIG. 14, an antenna device according to an eleventhembodiment of the present invention will be described below. FIG. 14 isa view showing the configuration of the antenna device according to theeleventh embodiment of the present invention. In FIG. 14, the referencenumerals 69, 70, 71, 72, 73, 74, 75 and 76 designate antenna elements;and 77, a high-frequency signal source.

Referring to FIG. 14, the operation of the antenna device according tothis embodiment will be described below. The feeding portion 77 and theantenna elements 69, 70 and 71, 72 operate in the same manner as in theantenna device according to the third embodiment in FIG. 6. The antennaelements 73, 74, and 75, 76 are connected in parallel to the antennaelements 69, 70 and 71, 72 so that the directions of main polarizationare made identical with each other whereas the directions of mainradiation cross perpendicularly to each other.

The antenna device configured as described above exhibits radiationcharacteristic in which the radiation directivity in the horizontalplane in terms of vertically polarized wave is concentrated into thefour directions X, −X, Y and −Y. A gain of about 5.5 dB is obtained ineach of the four directions. Radiation characteristic of about 30degrees as a half-value width can be obtained.

Also in this embodiment, the directivity in the vertical plane and inthe horizontal plane can be changed by changing the angle α in the bentportions.

As described above, in the antenna device according to the eleventhembodiment, a 4-directional antenna having desired directivity andhaving a high gain can be achieved with a simple configuration.

Twelfth Embodiment

Referring to FIG. 15, an antenna device according to a twelfthembodiment of the present invention will be described below. FIG. 15 isa view showing the configuration of the antenna device according to thetwelfth embodiment of the present invention. In FIG. 15, the referencenumerals 78, 79, 80, 81, 82 and 83 designate antenna elements; 84, afeeding portion; 85, a reflection plate; 86, 87, 88 and 89,high-frequency switches; and 90 and 91, shorting lines.

Referring to FIG. 15, the configuration of the antenna device accordingto this embodiment will be described below in more detail. The antennaelements 78, 79 and 80, 81 and the feeding portion 84 operate in thesame manner as in the antenna device according to the third embodimentin FIG. 6. The antenna elements 82 and 83 are connected in parallel tothe antenna elements 78, 79 and 80, 81. The antenna elements arearranged so that the directions of main polarization are made identicalwith each other whereas the directions of main radiation crossperpendicularly to each other. The high-frequency switches 86 and 87 andthe shorting line 90 are connected to the antenna elements 78 and 79 atpoints. When the high-frequency switches 86 and 87 are turned on, theantenna elements 78 and 79 and the shorting line 90 serve as aquarter-wavelength shorting stub in which the antenna elements do notcontribute to radiation. The antenna elements 80 and 81, thehigh-frequency switches 88 and 89 and the shorting line 91 operate inthe same manner as described above. Further, the reflection plate 85 isarranged so as to be separated by a distance 92 in the −X direction fromthe antenna elements 78, 79 and 80, 81.

Referring to FIG. 15, the operation of the antenna device according tothis embodiment will be described below. In the antenna deviceconfigured as described above, when the high-frequency switches 86 and87 are turned on while the high-frequency switches 88 and 89 are turnedoff, the antenna elements 78 and 79 do not contribute to radiation sothat radiation is concentrated into an intermediate direction betweenthe X direction and the Y direction. As a result, a gain of about 9 dBis obtained and radiation directivity of about 80 degrees as ahalf-value width is obtained. On the contrary, when the high-frequencyswitches 86 and 87 are turned off while the high-frequency switches 88and 89 are turned on, the direction of maximum radiation is directed tothe intermediate direction between the X direction and the −Y direction.

Also in this embodiment, the directivity in the vertical plane and inthe horizontal plane can be changed by changing the angle α in the bentportions.

As described above, in the antenna device according to the twelfthembodiment, antenna elements opposite to each other are partiallyconnected/disconnected to/from each other by electronic switches tothereby obtain desired directivity. Hence, a changeable directionalantenna having a high gain can be achieved with a simple configuration.

Thirteenth Embodiment

Referring to FIG. 16, an antenna device according to a thirteenthembodiment of the present invention will be described below. FIG. 16 isa view showing the configuration of the antenna device according to thethirteenth embodiment of the present invention. In FIG. 16, thereference numerals 93 and 94 designate antenna patterns (antennaelements); 95, a quarter-wavelength shorting stub; 96, a dielectricsubstrate; and 99, a high-frequency signal cable.

Referring to FIG. 16, the detailed configuration and operation of theantenna device according to the thirteenth embodiment of the presentinvention will be described below. The antenna patterns 93 and 94 andthe quarter-wavelength shorting stub 95 are constituted by a printpattern formed on the dielectric substrate 96. The antenna patterns 93and 94 operate in the same manner as in the antenna device according tothe fourth embodiment in FIG. 7. Impedance in the feeding portion 97between the antenna patterns 93 and 94 reaches a high value of severalkΩ. To match this impedance with the impedance (generally 50Ω) in thehigh-frequency signal cable 99, the high-frequency signal cable 99 isconnected to the quarter-wavelength shorting stub 95 at optimalpositions 98.

On this occasion, the quarter-wavelength shorting stub 95 does notincrease the total area of the antenna because the stub 95 is disposedinside the antenna patterns 93 and 94.

As described above, in the antenna device according to the thirteenthembodiment, a matching circuit is formed by the print pattern on thedielectric substrate. Hence, the antenna device can be achieved with asmall-size and simple planar configuration.

Fourteenth Embodiment

Referring to FIG. 17, an antenna device according to a fourteenthembodiment of the present invention will be described below. FIG. 17 isa view showing the configuration of the antenna device according to thefourteenth embodiment of the present invention. In FIG. 17, thereference numeral 100 designates a conductive plate; 101, a first slotelement as an antenna element; 102, a second slot element as an antennaelement; 101 a and 102 a, bent portions; and 103, a feeding portion.

The configuration of the antenna device according to this embodimentwill be described in more detail. Each of the first and second slotelements 101 and 102 is constituted by an opening portion provided inthe conductive plate 100. Each of the first and second slot elements 101and 102 is formed to have a length equal to one wavelength. Further, thefirst and second slot elements 101 and 102 are bent at an angle α in thebent portions 101 a and 102 a respectively in the center. As shown inFIG. 17, the first and second slot elements 101 and 102 are arranged indiamond-wise opposition to each other. The length of each side of thediamond shape is equal to a half wavelength (λ/2). The respectiveopening portions of one-ends of the first and second slot elements 101and 102 are connected to each other and a feeding portion 103 isprovided at this junction. The respective opening portions at theother-ends are not connected to each other.

Referring to FIG. 17, the operation of the antenna device according tothis embodiment will be described below. The antenna device configuredas described above is complementary to the antenna device according tothe first embodiment in FIG. 1. The operation of the antenna device ofthis embodiment can be explained in the same manner as that in theantenna device of the first embodiment if the electric currentsdistributed into the respective antenna elements in FIG. 1 are replacedby magnetic currents distributed into the respective slot elements inFIG. 17. Also in FIG. 17, vertically polarized wave is radiated. Maximumradiation is generated in the X direction and in the −X direction, sothat a directional gain of about 6 dB is obtained. When the angle α inthe bent portions is changed, radiation patterns in the horizontal planeand in the vertical plane can be changed greatly in the same manner asin the antenna device according to the first embodiment in FIG. 1. When,for example, the angle α in the bent portions is changed to increasefrom 30 degrees to 150 degrees, the half-value width of the radiationpattern in the horizontal plane changes from 40 degrees to 150 degreeswhereas the half-value width of the radiation pattern in the verticalplane changes from 78 degrees to 58 degrees.

Although this embodiment has shown the case where the direction of mainpolarization is vertical (Z), the antenna device shown in FIG. 17 canalso operate as a horizontal polarization antenna if the antenna deviceis arranged so as to be rotated by 90 degrees to thereby select thedirection of main polarization to be horizontal (Y).

As described above, in the antenna device according to the fourteenthembodiment, a slot antenna having desired directivity and having a highgain can be achieved with a simple planar configuration.

Fifteenth Embodiment

Referring to FIG. 18, an antenna device according to a fifteenthembodiment of the present invention will be described below. FIG. 18 isa view showing the configuration of the antenna device according to thefifteenth embodiment of the present invention. In FIG. 18, the referencenumeral 103 designates a feeding portion; 104, a conductive plate; 105,a first slot element as an antenna element; and 106, a second slotelement as an antenna element.

Referring to FIG. 18, the detailed configuration and operation of theantenna device according to the fifteenth embodiment of the presentinvention will be described below. Each of the first and second slotelements 105 and 106 is constituted by opening portions formed in theconductive plate 104. Each of the first and second slot elements 105 and106 is formed to have a length equal to two wavelengths. Further, eachof the first and second slot elements 105 and 106 is bent at an angle αin three places. The antenna device configured as described above iscomplementary to the antenna device according to the second embodimentin FIG. 5. In the antenna device shown in FIG. 17, vertically polarizedwave is radiated, so that maximum radiation is generated in the Xdirection and in the −X direction. A directional gain of about 8.5 dB isobtained. When the angle α is changed, radiation patterns in thehorizontal plane and in the vertical plane can be changed greatly in thesame manner as in the antenna device according to the second embodimentin FIG. 5. When, for example, the angle α is made to increase from 60degrees to 120 degrees, the half-value width of the radiation pattern inthe horizontal plane changes from 50 degrees to 65 degrees whereas thehalf-value width of the radiation pattern in the vertical plane changesfrom 50 degrees to 35 degrees.

As described above, in the antenna device according to the fifteenthembodiment, a slot antenna having desired directivity and having a highgain can be achieved with a simple planar configuration.

Sixteenth Embodiment

Referring to FIG. 19, an antenna device according to a sixteenthembodiment of the present invention will be described below. FIG. 19 isa view showing the configuration of the antenna device according to thesixteenth embodiment of the present invention. In FIG. 19, the referencenumeral 103 designates a feeding portion; 107, a conductive plate; 108and 110, first slot elements as antenna elements; and 109 and 111,second slot elements as antenna elements.

Referring to FIG. 19, the detailed configuration and operation of theantenna device according to the sixteenth embodiment of the presentinvention will be described below. The first slot elements 108 and 109and the second slot elements 110 and 111 operate in the same manner asin the antenna device according to the fourteenth embodiment in FIG. 17and are connected in parallel with each other at the feeding portion103. The antenna device configured as shown in FIG. 19 is complementaryto the antenna device according to the third embodiment shown in FIG. 6.In FIG. 19, vertically polarized wave is radiated, so that maximumradiation is generated in the X direction and in the −X direction. Adirectional gain of about 9 dB is obtained. When the angle α is changed,radiation patterns in the horizontal plane and in the vertical plane canbe changed greatly in the same manner as in the antenna device accordingto the third embodiment shown in FIG. 6.

Incidentally, although this embodiment has shown the case where twopairs of antenna devices according to the fourteenth embodiment shown inFIG. 17 are connected in parallel with each other, the directivity inthe vertical plane can be narrowed to obtain a higher directional gainif two pairs of antenna devices according to the fifteenth embodimentshown in FIG. 18 are connected in parallel with each other.

As described above, in the antenna device according to the sixteenthembodiment, a slot antenna having desired directivity and having a highgain can be achieved with a simple planar configuration.

Seventeenth Embodiment

Referring to FIG. 20, an antenna device according to a seventeenthembodiment of the present invention will be described below. FIG. 20 isa view showing the configuration of the antenna device according to theseventeenth embodiment of the present invention. In FIG. 20, thereference numeral 103 designates a feeding portion; 112, a dielectricsubstrate; 113, a conductor pattern; and 114, 115, 116 and 117, slotelements as antenna elements.

Referring to FIG. 20, the detailed configuration and operation of theantenna device according to the seventeenth embodiment of the presentinvention will be described below. The conductor pattern 113 isconstituted by a print pattern formed on the dielectric substrate 112.The slot elements 114, 115, 116 and 117 are constituted by openingportions provided in the conductor pattern 113. When, for example, theeffective relative dielectric constant of the dielectric substrate 112is 2, the length of each of the slot elements 114, 115, 116 and 117 isreduced to about a half as large as the length of corresponding one ofthe first and second slot elements 108, 109, 110 and 111 in the antennadevice shown in FIG. 19 because the wavelength on the dielectricsubstrate 112 is reduced to about a half as large as the wavelength in afree space. The antenna device configured as described above operates inthe same manner as the antenna device shown in FIG. 19.

Incidentally, also in this embodiment, radiation patterns in thehorizontal plane and in the vertical plane can be controlled by changingthe angle α in the bent portions. As described above, in the antennadevice according to the seventeenth embodiment, a slot antenna havingdesired directivity and having a high gain can be achieved with asmall-size and simple planar configuration.

Eighteenth Embodiment

Referring to FIG. 21, an antenna device according to an eighteenthembodiment of the present invention will be described below. FIG. 21 isa view showing the configuration of the antenna device according to theeighteenth embodiment of the present invention. In FIG. 21, thereference numeral 103 designates a feeding portion; 107, a conductiveplate; 108 and 110, first slot elements as antenna elements; 109 and111, second slot elements as antenna elements; and 118, a reflectionplate.

Referring to FIG. 21, the detailed configuration and operation of theantenna device according to the eighteenth embodiment of the presentinvention will be described below. The conductive plate 107, the firstand second slot elements 108, 109, 110 and 111 and the feeding portion103 operate in the same manner as in the antenna device according to thesixteenth embodiment shown in FIG. 19. The reflection plate 118 isarranged so as to be separated by a distance 119 in the −X directionfrom the conductive plate 107.

The conductive plate 107, the first and second slot elements 108, 109,110 and 111 and the feeding portion 103 generate maximum radiation inthe X direction and in the −X direction. Wave radiated in the −Xdirection is reflected by the reflection plate 118, so that thereflected wave is radiated in the X direction. Hence, radiation patternsare concentrated into the X direction. When the distance 119 of thereflection plate 118 is selected to be about 0.3λ (0.3 times as large asthe wavelength), a directional gain of about 12.5 dB can be obtained inthe X direction.

Incidentally, also in this embodiment, radiation patterns in thehorizontal plane and in the vertical plane can be controlled by changingthe angle α in the bent portions.

As described above, in the antenna device according to the eighteenthembodiment, a slot antenna having desired directivity and having a highgain can be achieved with a simple planar configuration.

Nineteenth Embodiment

Referring to FIG. 22, a radio apparatus with an antenna deviceconfigured according to a nineteenth embodiment of the present inventionwill be described below. FIG. 22 is a view showing the configuration ofthe antenna device according to the nineteenth embodiment of the presentinvention. In FIG. 22, the reference numeral 119 designates an antennadevice; 120, a high-frequency cable; 121, a reflection plate; 122, aradio circuit portion; and 123, an antenna cover.

The configuration of the radio apparatus according to this embodimentwill be described below in more detail. The reflection plate 121 isdisposed on one side surface of the radio circuit portion 122. Theantenna device 119 is disposed so as to be separated by a fixed distance(for example, 0.3λ) from the reflection plate 121. The high-frequencycable 120 is connected from the radio circuit portion 122 to the antennadevice 119 so that the antenna device 119 is fed. The antenna device 119is protected by the antenna cover 123. The antenna device 119 operatesin the same manner as the antenna device according to the thirteenthembodiment shown in FIG. 16.

Referring to FIG. 22, the operation of the radio apparatus according tothis embodiment will be described below. In the radio apparatusconfigured as described above, radiation from the antenna device 119 isconcentrated into the direction of the arrow 124 by the reflection plate121. Thus, a directional gain of about 9.5 dB can be obtained. Hence,antenna characteristic is not affected by the radio circuit portion 122.Further, the radio circuit portion 122 is not affected by electric waveradiated from the antenna device 119.

Further, it is sufficient if the distance between the reflection plate121 and the antenna device 119 is about 0.3λ (about 45 mm for theoperating frequency of 1900 MHz). Accordingly, the radio apparatushaving the built-in antenna can be made compact. Hence, if the radioapparatus is applied to a fixed terminal equipment or to a radio basestation, desired radiation directivity can be obtained with a small-sizeand simple configuration. Hence, a fixed terminal equipment or a radiobase station with a built-in antenna having a high gain can be achieved.

Incidentally, the configuration of the radio apparatus and the antennadevice is not limited to this embodiment and the same effect asdescribed above can be obtained if the same structure as described aboveis provided.

As described above, in the radio apparatus according to the nineteenthembodiment, a radio apparatus with a built-in antenna having desireddirectivity and having a high gain can be achieved with a small-size andsimple configuration.

Twentieth Embodiment

Referring to FIG. 23, an antenna device according to a twentiethembodiment of the present invention will be described below. FIG. 23 isa view showing the configuration of the antenna device according to thetwentieth embodiment of the present invention. In FIG. 23, the referencenumerals 125, 126, 127 and 128 designate antenna devices; 129 and 130,reflection plates; 131, 132, 133, 134 and 135, fittings; 136, a firstantenna system; 137, a second antenna system; and 138, a pole.

Referring to FIG. 23, the detailed configuration and operation of theantenna device according to the twentieth embodiment of the presentinvention will be described below. The antenna devices 125, 126, 127 and128 operate in the same manner as the antenna device according to thethirteenth embodiment shown in FIG. 16. The antenna devices 125 and 126are arranged in 180 degrees-opposition to each other through thereflection plate 129 and fixed by the fittings 131 and 132. Thus, afirst antenna system 136 is formed. Similarly, the antenna devices 127and 128 are arranged in 180 degrees-opposition to each other through thereflection plate 130 and fixed by the fittings 133 and 134. Thus, asecond antenna system 137 is formed. The first and second antennasystems 136 and 137 are fixed to each other by the fittings 135 so as tobe separated by a fixed distance (generally a distance of one wavelengthor larger) from each other, so that they serve as a diversity antenna.

Here, in the first antenna system 136, the antenna device 125 exhibitsradiation directivity of about 180 degrees as a half-value width in theX direction because of the effect of the reflection plate 129, so thatthe gain in the −X direction becomes lower by about 10 dB than the gainin the X direction. On the other hand, the antenna device 126 exhibitsradiation directivity of about 180 degrees as a half-value width in the−X direction because of the effect of the reflection plate 129, so thatthe gain in the X direction becomes lower by about 10 dB than the gainin the −X direction. As described above, the reflection plate 129 isused in common to the antenna devices 125 and 126. Also the secondantenna system 137 operates in the same manner as the first antennasystem 136.

Incidentally, the antenna device and the arrangement and configurationthereof are not limited to this embodiment and the same effect asdescribed above can be obtained if the same structure as described aboveis provided.

As described above, in the antenna device according to the twentiethembodiment, a sector diversity antenna constituted by a plurality ofantennas arranged therein and having a high gain with desireddirectivity can be achieved with a small-size and simple configuration.

INDUSTRIAL APPLICABILITY

According to the present invention, an antenna device configured asdescribed above particularly has two antenna devices arranged indiamond-wise opposition to each other so that one-end of each antennaelement is fed whereas the other-end of the antenna element is opened.Each of the antenna elements of the antenna device is bent at an angle αin its center to there by select the angle α to be an angle at whichoptimal radiation directivity can be obtained. Hence, desired optimalradiation directivity can be obtained with a simple planarconfiguration. Hence, an antenna device having a high gain can beachieved.

Further, according to the present invention, also in the case whereantenna elements are particularly constituted by a print pattern on adielectric substrate, desired radiation directivity can be obtained witha small-size and simple planar configuration. Hence, an antenna devicehaving a high gain can be achieved.

Further, according to the present invention, two pairs of antennadevices are particularly arranged with the directions of mainpolarization crossing perpendicularly to each other so that the twopairs of antenna devices are fed with their phases which are differentby 90 degrees from each other. Hence, the desired radiation directivitycan be obtained with a simple planar configuration. Hence, a circularpolarization antenna having a high gain can be achieved.

Further, according to the present invention, a plurality of antennadevices are particularly arranged with the directions of mainpolarization being made identical with each other and with thedirections of main radiation being made different from each other sothat opposite antenna elements in one or plural antenna devices arepartially electronically connected/disconnected to/from each other.Hence, the radiation directivity can be changed variously to obtaindesired directivity with a simple configuration. Hence, a changeabledirectional antenna device having a high gain can be obtained.

Further, according to the present invention, a quarter-wavelengthshorting stub is particularly connected to feeding points so thatfeeding is performed at a position where the impedance of the shortingstub is optimized. Hence, good impedance matching can be obtained by asmall-size matching circuit with a simple configuration. Hence, anantenna device having a high gain can be provided.

Further, according to the present invention, an antenna deviceparticularly has slot elements provided in two conductive plates andarranged in diamond-wise opposition to each other so that one-end ofeach slot element is fed whereas the other-end of the slot element isopened. Each of the slot elements of the antenna device is bent at anangle α in its center to thereby select the angle α to be an angle atwhich optimal radiation directivity can be obtained. Hence, desiredradiation directivity can be obtained with a simple planarconfiguration. Hence, a slot antenna having a high gain can be achieved.

Further, according to the present invention, a radio apparatus has abuilt-in antenna device in which two antenna elements are arranged indiamond-wise opposition to each other so that one-end of each antennaelement is fed whereas the other-end of the antenna element is opened.Each of the antenna elements of the antenna device is bent at an angle αin its center to thereby select the angle α to be an angle at whichoptimal radiation directivity can be obtained. Hence, a radio apparatushaving a built-in antenna with desired directivity and a high gain witha small-size and simple configuration can be provided.

Further, according to the present invention, particularly one reflectionplate is used in common to a plurality of antenna devices. Hence,desired radiation directivity can be obtained with a small-size andsimple configuration. Hence, a diversity or sector antenna having a highgain can be achieved.

Further, according to the present invention, particularly a radioapparatus with a built-in antenna device according to any one ofembodiments of the present invention is mounted. Hence, desiredradiation directivity can be obtained in a small-size and simpleconfiguration. Hence, a diversity or sector antenna having a high gaincan be used in a radio base station.

What is claimed is:
 1. A plurality of antenna devices, each antennadevice comprising a first one-wavelength antenna element bent at anangle α in a center of said first antenna element, and a secondone-wavelength antenna element bent at an angle α in a center of saidsecond antenna element, wherein said first and second antenna elementsare arranged in diamond-wise opposition to each other, wherein a feedingportion is disposed at one-end of said first and second antennaelements, wherein another end of said first and second antenna elementsis open, and wherein said angle α is selected to be an optimal angle,wherein said plurality of antenna devices are arranged such thatdirections of main polarization of each antenna device are madeidentical with each other while directions of main radiation are madedifferent from each other, and still further wherein opposite antennaelements of at least one antenna device among said plurality of antennadevices are partially electronically connected/disconnected to/from eachother.